Thesis
Optimal management of an emerging pathogen
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2025
- Thesis identifier
- T17473
- Person Identifier (Local)
- 201980545
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Emerging pests and pathogens have potentially devastating environmental, ecological and economic consequences, making their early control an imperative. There is an increased interest in designing management strategies that reduce the rate of arrival and spread of a pathogen (‘precautionary’ management) and are frequently promoted as preferable. However, in practice, management strategies are often only deployed once an outbreak has been detected (‘reactionary’ management). With the frequency of pest outbreaks likely to increase, a key policy question is how to deploy resources to reduce their potentially irreversible impact. In this thesis, we create a deterministic bioeconomic model to examine how the optimal level of precautionary management (which is restricted by a budget) changes when the key characteristics of the pest and its economic impact are changed. We show that when a reactive management strategy is unavailable, the optimal level of precautionary management increases as the primary and secondary disease transmission rates and the loss (caused by disease) are increased. This trend still holds when a reactive management strategy is available, except for a small range of loss values (caused by disease), where it is optimal to wait and deploy the reactive strategy only. We show that the optimal management strategy is highly sensitive to small changes in the effectiveness of both precautionary and reactive management. The deterministic model is modified to include random arrival to find the optimal management strategy and the difference between deterministic and stochastic results. We introduce uncertainty into the deterministic model using the absolute value of a normal distribution and log-normal distribution. We extend the “profit” function by an exponential utility function to include risk attitude. So, allocation of resources changes when utility function changes and managers become more risk-averse for both precautionary and reactive management strategies. The key policy question is how to reduce the potentially irreversible impact of pathogens on the environment. Biosecurity measures are implemented to reduce (or eliminate) the risk of introducing pathogens from outside the country (or region) both for prevention and reactive measures. These reactive actions are intended to reduce the present and future economic and environmental losses caused by the arrival of pathogens. Sensitivity analysis highlights that the optimal management strategy is very sensitive to small changes in the effectiveness of both precautionary and reactive management. The optimal control theory is employed to help the decision maker determine the paths of expenditure that minimise the present value of the costs associated with disease over a fixed period. The analysis quantified the uncertainty associated with disease predictions by running multiple simulations with different parameter values. By simulating multiple scenarios and analysing the results, we gain valuable insight into the interaction between the random arrival of the pathogen, the spread of the disease, and the effectiveness of the management. It provided a range of potential disease outcomes, aiding in risk assessment and decision-making under uncertainty. The research affirmed the importance of adopting risk management strategies for farmers and stakeholders to navigate uncertainties in plant and agricultural activities. Using risk management tools indicates an interconnected relationship between different risk management strategies.
- Advisor / supervisor
- Kleczkowski, Adam
- Resource Type
Relations
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PDF of thesis T17473 | 2025-10-20 | Public | Download |